National leader Judith Collins isn't upset about the latest four polls showing National's support languishing in the 20s. 

In fact, she's pondering whether the polls show a permanent realignment of the centre-right bloc, thanks to Act's resurgence as a credible party. 

"What is really important to remember is there is a centre-right vote and the centre-right votes are in every poll consistently going up," Collins said. 

When asked if she hoped this was a permanent shift she said "I hope so". 

When asked to clarify this, she shifted position. 

"It's up to the voters. The only way to change the Government is National and that's the message to people," Collins said. 

Collins said National and Act would almost inevitably form a government together, which was why the strong polling for both together was not as bad as it might appear. 

"Certainly when I've been in Government in Parliament we've always been in coalition with Act," Collins said, although these agreements were confidence and supply agreements. 

While Labour and the Greens have historically managed to coexist with the Greens not dipping below 5 per cent no matter how well Labour polls, National and Act have, in the last decade, eaten away at each other's polling. 

When National's polling climbs, Act's tends to drop so low it's required National's support to retain the only seat it can, in the form of an electorate deal in Epsom. 

A permanent realignment could mean National ditching that deal and trying to win Epsom back. 

"These things are always up every election, we discuss them," Collins said, of the Epsom deal. 

Former National leader Simon Bridges was forced to confront this problem during his tenure as leader. 

Bridges took the unprecedented step of allowing then-MP Alfred Ngaro to openly contemplate splitting from National to set up his own party. 

Reflecting on this, Collins acknowledged under MMP "you've got to have friends". 

"You're always going to see people deciding between elections particularly when they've voted differently from what they normally would," Collins said. 

Perhaps sending a signal to Bridges, who is tipped to be challenging Collins for the leadership, Collins said that regardless of what happens, she plans to stick around in Parliament for the long haul. 

This could be something of a warning to camp Bridges, who would prefer Collins exited Parliament than cause trouble from the backbench. 

"I don't think anyone should think that I'm a quitter," Collins said, adding she'd serve the constituents of her Papakura electorate "as long as they want me". 

Collins has recently copped flak, along with the Government, for her housing accord with Labour. 

The accord would make it far easier to build more housing in cities, bringing on far more housing supply and hopefully lowering prices. 

But MPs in New Zealand's leafier suburbs are concerned the accord will winnow away at their support - and National MPs are worried it will lead to electoral rout, with Act making gains from its opposition to the rules. 

For now Collins is sticking with the accord - and with her decision to join forces with Labour. 

"We certainly want to deliver more houses but I believe Labour does as well, and what I believe is really important is people have more houses," Collins said. 

However, she said she would keep an open mind to changes proposed by the select committee. 

"We have very hard MPs on that select committee in the form of Nicola Willis and Scott Simpson. 

"They will be talking through any changes that need to be made," Collins said. 

"It's also important to remember the Auckland Unitary Plan, which is in place already, also allows for a tremendous amount of intensification," she said.